Sciencey odd question just occured in my daily musings...

[fuzzy]

Ah, but we are now back on earth (post 59) so subject to the usual forces :lol:

stop trying to simplify things tamz

 

[fuzzy]

NO there is no gravity in space therefore the water would be weightless

are you just an earth plumber? not got your 'moon' ticket? Ask at your local centre, when your doing heat pumps

 

[WaterTight]

Well I'm still a bit confused but I think the answer is too many other factors would get in the way of the experiment.

I suppose what I want to imagine is say you are on this magical world for this experiment - you have this level stretch of 1000 miles of pipe, which is not effected by friction, is neither subject to the effects of gravity nor the effects of no gravity, where the only thing being tested, somehow - magically - is whether the mass of this water itself can hold back pressure when applied.

So this pipe would be full of water but not pressurised. Just at the pressure it normally would be at. At the far end is a tap which will be opened shortly. Then, 1000 miles back the other away is a valve which is closed. On the other side of the valve is more pipe, containing water which is pressurised to 1.5 bar. If you open the valve the pressurised water comes into contact with the non-pressurised water, sitting there for it's 1000 mile stretch - if you then open the tap 1000 miles away does water come out or not?

 

[WaterTight]

And if this has now been answered already and I'm just too thick to get it and everyone else does I apologise and will stop bothering everyone :43:

 

[unguided1]

not answerd yet dont forget if a pipe is a 1000 miles long layin on a planet, the natural curvature of the planet will allow air in when you open the pipe allowing the water to pour out

 

[fuzzy]

Well I'm still a bit confused but I think the answer is too many other factors would get in the way of the experiment.

I suppose what I want to imagine is say you are on this magical world for this experiment - you have this level stretch of 1000 miles of pipe, which is not effected by friction, is neither subject to the effects of gravity nor the effects of no gravity, where the only thing being tested, somehow - magically - is whether the mass of this water itself can hold back pressure when applied.

So this pipe would be full of water but not pressurised. Just at the pressure it normally would be at. At the far end is a tap which will be opened shortly. Then, 1000 miles back the other away is a valve which is closed. On the other side of the valve is more pipe, containing water which is pressurised to 1.5 bar. If you open the valve the pressurised water comes into contact with the non-pressurised water, sitting there for it's 1000 mile stretch - if you then open the tap 1000 miles away does water come out or not?

no, the weight of water would be too much for 1.5 bar to overcome it

 

[fuzzy]

not answerd yet dont forget if a pipe is a 1000 miles long layin on a planet, the natural curvature of the planet will allow air in when you open the pipe allowing the water to pour out

arrrhhhhh

ok, lets also pretend the earth is flat

 

[WaterTight]

no, the weight of water would be too much for 1.5 bar to overcome it

Soooo.....what we want to know is, how long would a piece of 15mm copper full of water need to be when subjected to 1.5 bar before water couldn't come out of the other end but ONLY because the weight of the water in said pipe would be too great for it to be pushed out by available pressure?

I've done the calculations and its 643.274653 miles. No need to check, 100% accurate, absolutely.

 

[GQuigley67]

I'm sorry guys but water would boil in space, thats what happens to you in space the water inside yer body boils !

ohh and did you know that at the deepest part of the ocean the mariana trench(6.85miles) the pressure is over 8 tons per square inch ?? lol

 

[Mrs Tara Plumbi]

Only just read this gem of a thread - physics, maths and astonomy - my all time favourite subjects, appart from a few not taught in my catholic school!

In deep space the temperature is just 3 degrees warmer than absolute 0 so approx -270 C
So the water will definitely freeze.
Not sure what happens to copper or plastic at these temperatures.

As said earlier if there were no forces such as gravity or friction then ANY body set in motion will continue to move in a staight line at a constant speed, as in a vacuum or deep space.
In side the theoretical frictionless pipe the water release at mains pressure will continue to move at the same speed BUT i think you question is that this water then meets an obstacle which is the still water sitting in the pipe.
So you need enough pressure to move the still water. Sorry if i am repeating what was said..

I'm not sure the moon will have any effect on the water in the miles of pipe. Because I think the moon - tide thing is to do with a big body of water like a giant swimming pool. Along this theoretical pipe there is always a small amount of water in any one place.

 

[GQuigley67]

it actually boils before it freezes then turns into ice droplets

 

[Mrs Tara Plumbi]

While you were writing I was checking my facts!
of course I forgot that water boilers at lower temperature when pressure drops.
I don't know what the pressure is in deep space?

But I was thinking of comets and rocks like pluto being largely frozen ice. But of course they have mass and pressumably higher pressure than deep space. Makes you think...

 

[GQuigley67]

[DLMURL="http://scienceblogs.com/startswithabang/2009/06/water_in_space_what_happens.php"]Water in Space: What Happens? : Starts With A Bang[/DLMURL]

interesting page

 

[GQuigley67]

sorry correction, it boils faster than freezing so in effect it is freezing but turning into a gas at the same time lol mad

 

[diamondgas]

do you have 25 mile of copper on the van?

diamondgas wants to do it in speedfit, but i think thats cheating, in fact ive decided hes a big wuss now and i o longer consider him a real plumber, psss, dont tell him

how about doing it in iron? ive got some hand dies

I have'n got a finger big enough for iron fuzzy and i am a wuss .... Part time plumber full time gas engineer :rofl: Haven't got a clue when in comes to anything waste related and have never fancied messing with toilets, baths and the like... leave that to the proffesionals lol ...

 

[Mrs Tara Plumbi]

And this covers a lot of useful stuff but doesn't quite anwswer the question
Domestic water-supply system - theory - JohnHearfield.com

this chap does know Renolds

 

[GQuigley67]

And this covers a lot of useful stuff but doesn't quite anwswer the question
Domestic water-supply system - theory - JohnHearfield.com

this chap does know Renolds

thats 1st year stuff lol

 

[fuzzy]

Soooo.....what we want to know is, how long would a piece of 15mm copper full of water need to be when subjected to 1.5 bar before water couldn't come out of the other end but ONLY because the weight of the water in said pipe would be too great for it to be pushed out by available pressure?

I've done the calculations and its 643.274653 miles. No need to check, 100% accurate, absolutely.

so your saying we are good for the first 642 miles?

 

[fuzzy]

I have'n got a finger big enough for iron fuzzy and i am a wuss .... Part time plumber full time gas engineer :rofl: Haven't got a clue when in comes to anything waste related and have never fancied messing with toilets, baths and the like... leave that to the proffesionals lol ...

its all very clear now, so how far would gas travel if subjected to a force of 1.5bar in a 15mm copper tube?

 

[diamondgas]

its all very clear now, so how far would gas travel if subjected to a force of 1.5bar in a 15mm copper tube?

Up hill, down or on the level? I'd be gettn' the meter gov checked if I was getting that sort of presure ... imagine the cooker flame!!! lol

 

[TGor]

Lot's of smoke and mirrors on this one guys. I wonder when they stopped teaching the Hydraulic Gradient phenomenon to plumbers?? ; anyhow our plumbing teacher used to have a rig with 1/4" dia horizontal pipe about 2 metres long with a tap on one end. There were vertical branches (open ended) from the pipe at about 200mm intervals in glass pipe about 400mm high. and the end branch away from the tap end had a bit of a reservoir which was filled with coloured water, firstly with the tap closed so that the whole rig was filled and you could see coloured water at equal heights in each vertical branch. When the tap was opened and the water flowed the level in each branch dropped but not equally so that you could actually run a line through from the resevoir to the tap. This was to demonstrate the difference between Static Pressure and Hydraulic pressure .. that is when water flows through a pipe it loses pressure due to friction against the pipe wall.So in this way you would be able to easily find out if the original question is true by setting up a bigger scale rig (but still with 1/4") and experiment with the reservoir height and length of pipe till nothing comes out. Good luck

 

[fuzzy]

that sounds interesting any chance of a skethc or link to it happening on you tube or something?

 

[fuzzy]

Up hill, down or on the level? I'd be gettn' the meter gov checked if I was getting that sort of presure ... imagine the cooker flame!!! lol

imagine how quick youd cook a pizza

 

[WaterTight]

For me, personally, it turns out I had a big enough brain to think up the question but far too small a brain to understand half the answers. But since ignorance is evidently bliss I'm not complaining.

 

[Mrs Tara Plumbi]

I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.

 

[villa_tom]

I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.

My brain just burst :willy_nilly:

 

[unguided1]

I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.

Yeah wot evar but is it enough fer the loveslave ter fill the kettle?????

 

[WaterTight]

I couldn’t let the challenge of this question leave my head
I think the friction is irrelevant and I think the amount of water in the pipe needs to be big enough to be exerting and equal and opposite force to the mains pressure
I may have the answer found in a plumbing book as to when the 3 bar of mains pressure runs out, I could be very wrong.
Please check my maths I may have made massive mistakes.

Townsend Plumbing 1 second edition 1969

Pages 51-3 chapter about water.

If we assume water pressure of 3 bar = 30 m head
And 15mm pipework

Intensity of pressure = head x 9.8 kilo Newton kN/m2
= 294 kN/m2
Total pressure = intensity of pressure x area
Total pressure = 294 kN/m2 x (3.142 x 7.52) m2= 51,961 kN

1 tonne of force = 1000 kg f = 9800 newtons = 1m3 of water

Therefore:
51,961 / 9.8 = 5,302 tonnes = 53,020m3 or 53 million litres of water

I think this means that 3 bar mains water pressure is enough to move 5,302 tonnes of water through a 15mm pipe

A litre is 1cm3 of water and if this pipe hold 0.15 litres per metre then 150 litre per km

At this point I have lost interest and Big Bang has come on TV … come on I’m nearly there.

353,467 kilometres of pipe filled with water.
By the way, circumference of the earth is a little over 40,000. so to all practical terestrial purposes the water will never stop coming.

.....Guh?

 

[fuzzy]

see if i got this, if you have 353,467km of 15mm tube, 3 bar is sufficient?

 

[Mrs Tara Plumbi]

see if i got this, if you have 353,467km of 15mm tube, 3 bar is sufficient?

Fuzzy - exactly the opposit
3 bar will not move this amount of water!

As I said:
1. i may have made a mistake with the maths as this seems a really big number, the the principles were right but my sums wrong OR
2. these formulas might be completely the wrong way of working out the answer

And - as when the computer said the answer is 42 then they set off to fing out the question.
the question i think i have tried to answer is if pipe was laid completely flat, no bends, how much standing water would be in the pipe before you could turn on 3 bars of mains pressure but not move anything?

Me thinks this should be addressed to some maths forum or we should just stick with the experiment as discussed.
What are the chances of winning lottery funding to fund the experiement which will prove my answer correct or incorrect?

 

[fuzzy]

thanks tara, good effort

i love the maths, when i get chance ill work through the sums and tell you how far 3bar can push

 

[TGor]

This is a sketch of the hydraulic gradient rig as I remember it! The difference in head seen at each vertical is caused by the friction loss due to flow in the pipe. This rig demonstrates it in a really practical way .. of course there are many formulae and methods to calculate theoretical friction losses in pipework systems but seeing is believing!!

 

[TGor]

Mrs Tara Plumbing .. friction is not irrelavent ot the question as if there were no friction there would be pressure loss and that is the key to this question.

pressure losses due to friction between th water flowing and the pipe wall are a function of the velocity (and a few other things like pipe roughness etc.) the higher the pressure the higher the velocity the higher the pressure loss .. therefore as the water runs through this imaginary endless pipe the pressure will gradually reduce proportionally to the loss due to friction and thus the velocity will reduce and so the loss will reduce and so on and so and until there will be such little velocity that there is hardly any loss and the pipe will not run full and it will trickle out but never stop fully as the flow and friction will reach equilibrium.

There is a true story about an engineer in Western Australia that ran a 30" water pipe from Perth to Kalgoorlie to the western goldfields a total length of 330 miles and the water took only 2 day to get there. The engineer commited suicide towards the end of the project because everyone was saying it wouldn't work!!

Interesting stuff this thanks all!

 

[dontknowitall]

Hmmm ...

View attachment 3465

 

[Kimou]

Gravity can't be dismissed. It's relative to pressure. It's like doing an experiment on the shadow of a 5p coin but removing the coin.

The moon affects the tides by proxy. It affects airs pressures which in turn compress and releases pressures on the oceans.

This pipe would have to be lined in exact ratio to the sea as no land mass will keep constant levels for the duration of such lengths.But by gradual reduction due to friction it will inevitably reduce to a trickle. This trick will eventually still manage to pass out the other end due to water's property of adhesion so cutting an inch off the terminal will not result in a sudden gush of pressure due to that pressure being exhausted miles ago.